Neptunium is a transuranium, radioactive element in the actinide series. It is denoted by the atomic symbol Np, it has the atomic number 93, and it has an atomic weight of 237. It is a silvery metal with a melting point of 1191.2°F (644° C). Its most stable isotope is neptunium-237, and fifteen more have been produced. The pure metal can be obtained by reducing neptunium (III) fluoride with lithium or barium vapor at about 2192°F (1200° C).

The discovery of the neutron in 1932 opened up some exciting new lines of research for scientists. One area that soon attracted a number of researchers involved nuclear changes known as (n,&ggr;) reactions. When substances are bombarded with neutrons (the "n" in n,&ggr;), they may incorporate the neutrons into their nuclei to produce new isotopes with an atomic weight one greater than that of the original isotope. In the...